Cam operated, pivoted contact switch assembly having split housing and safety cover

ABSTRACT

A switch assembly includes a housing forming a cavity in which are mounted a number of pairs of similar terminals. Each terminal includes a spring contact loop portion, and the pairs of terminals are mounted in opposed positions in the housing with the contact portions normally abutting in the closed circuit condition. A switch operator is pivotally mounted in the cavity and includes a cam surface for separating the contacts upon rotation of the operator. The cam and terminals are contoured for indexing the operator in its closed circuit and open circuit positions. The operator includes trunnions received with a snap fit into bearings formed integrally with the housing. A cover may be removably attached to the housing and includes structure for preventing inadvertent operation of the switch when the cover is in place.

United States Patent 1191 1111 3,883,705

Sebastian et al. May 13, 1975 [5 CAM OPERATED, PIVOTED CONTACT 3,131,265 4/1964 Toruk 200/6 BB SWITCH ASSEMBLY HAVING SPLIT 3,524,952 8/1970 Anderson et al. HOUSING AND SAFETY COVER 3,62l,l57 ll/l97l Schwab 200/6 BB [75] Inventors: Robert W. Sebastian, Wheaton; primary R. Scott Harry olsonv woodndge; Attorney, Agent, or FirmMason, Kolehmainen, Thomas F. Silberg, Downers Grove, Rathbum & w all of I11.

[73] Assignee: Molex Incorporated, Lisle, Ill. ABSTRACT [22] Filed. Jan. 11 1974 A switch assembly includes a housing forming a cavity in which are mounted a number of pairs of similar ter PP .2 32,555 minals. Each terminal includes a spring contact loop portion, and the pairs of terminals are mounted in op- 52 s Cl H 200 B; 200 153 LB; 200 275 posed positions in the housing with the contact POI- 2O0/3O3. 200/333 tions normally abutting in the closed circuit condition. 51 1111. C1. H0111 21/80 A Switch operawr is PivOtallY named in the cavity [58] Field of Search 200/1 R 6 R 6 C and includes a cam surface for separating the contacts 200/17 R 42 R, 50 A, 153 LB 154, 239 upon rotation of the operator. The cam and terminals 245 275, 283, 284, 293, 303 329 333, 334 are contoured for indexing the operator in its closed 335, 339 circuit and open circuit positions. The operator includes trunnions received with a snap fit into bearings [56] References Cited formed integrallg with Lhehhousing. 1: cove:i may be removably attac ed to t e ousing an inc u es struc- UNITED STATES PATENTS ture for preventing inadvertent operation of the switch 2,813,938 11 1957 Speizman 200 333 x when the cover is in place, 2,880,29l 3/1959 Bussmann 200/245 X 2,960,580 ll/l960 Aquillon 200/6 BB 20 Claims, 9 Drawing Figures I ATENTEB NM 1 31975 SHEET 2 OF 2 CAM OPERATED, PIVOTED CONTACT SWITCH ASSEMBLY HAVING SPLIT HOUSING AND SAFETY COVER The present invention relates to an improved switch assembly.

Manually operated switches are widely used in many environments for a variety of control functions. For some uses it is desirable to make possible the capability of carrying out multiple switching operations in a minimum space. One example can be found in programming applications where it has been proposed to incorporate several individual switch devices in a small housing or package capable of being mounted on a printed circuit board. Most switch structures presently available cannot readily be reduced in size sufficiently to be accommodated in a small space, such as in a standard dual-in-line package for printed circuit board mounting. Moreover, known switch structures developed for this and other purposes suffer from disadvantages such as complexity, expense, difficulty in assembly, and unreliability in operation under various conditions.

Important objects of the present invention are to provide a switch assembly including several individual switches in a small package; to provide a switch assembly wherein the number and complexity of parts are reduced to a minimum; to provide a quickly and easily assembled switch assembly; to provide a switch assembly wherein switching and indexing functions are carried out in a reliable and simple manner; to provide a switching assembly wherein inadvertent switch operation is prevented; and, generally, to provide a switch assembly overcoming disadvantages of known switch .structures and characterized by simplicity, ease of manufacture, reliable operation, and low cost.

In brief, a switch assembly constructed in accordance with the present invention may comprise a compact, simple arrangement including only four basic parts. A housing includes a top wall and opposed side walls defining a cavity, and one or more pairs of similar terminals are mounted in the cavity with spring contact portions abutted against one another in the closed circuit condition. A switch operator is pivotally mounted adjacent each terminal pair and includes a cam for selectively separating the contact portions. In accordance with the invention, the terminals and cam are contoured for indexing the operator in both the open circuit and closed circuit positions.

In accordance with another feature of the invention, each operator includes trunnions received in bearings formed integrally with the housing. In order to simplify assembly of the parts, the bearings and trunnions are arranged for a snap fit of the operator into the housing Each operator includes an actuating element ext'ending through the housing top wall for manual movement of the operator between closed and open circuit positions. One feature of the invention resides in the provision of a cover for the housing including structure for preventing movement of the operators between positions when the cover is in place.

The above and other objects and advantages of the present invention may be best understood from the following detailed description of the embodiments of the invention shown, in the accompanying drawings,

wherein: v

FIG. lis a perspective view of a switch assembly constructed in accordance with the present invention;

FIG. 2 is another perspective view of the assembly of FIG. 1;

FIG. 3 is a sectional view on an enlarged scale taken along the line 33 of FIG. 1;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is a partial sectional view taken along the line 55 of FIG. 3;

FIG. 6 is a sectional view similar to FIG. 3 illustrating the switch assembly in an alternate condition;

FIG. 7 is a perspective, exploded view of the assembly of FIG. 1 illustrating its parts in unassembled condition; 1

FIG. 8 is a side view, partly broken away, illustrating an alternative embodiment of the present invention; and

FIG. 9 is an end view, partly in section along the line 99 of FIG. 8, of the assembly of FIG. 8.

Having reference now to the drawings, in FIGS. 1-7 there is illustrated a switch assembly designated as a whole by the reference numeral 20 and constructed in accordance with the principles of the present invention. In general, the assembly 20 includes four individual switch structures or switches designated as 22, 24, 26 and 28 each manually operable between open circuit and closed circuit conditions. Due to the simplicity and compact nature of the assembly 20, the assembly 20 may, as illustrated, comprise a dual-in-line package or DIP package having extending male contacts 30 located on, for example, 0.100 inch centers. It should be understood that the principles of the present invention may be applied to switch assemblies including fewer or more individual switch structures arranged in configurations other than the illustrated DIP package.

In accordance with an important feature of the invention, the assembly 20 is made up of only four basic parts these being a housing generally designated as 32, a base generally designated as 34, a number of identical terminals, each generally designated as 36, and a number of identical switch operators, each generally designated as 38. In view of the fact that the entire assembly is made up of these few parts, substantial reductions are obtained in tooling costs, material costs, and assembly costs.

In general, each individual switch structure 22, 24, 26 and 28 includes a pair of terminals 36 mounted in normally abutting relation within a cavity 40 defined in the housing 32. Each switch structure further includes a switch operator 38 pivotally mounted within the housing 32 and movable between the closed circuit position of FIG. 3 and the open circuit condition of FIG. 6 wherein the terminals 36 are separated from one another. In accordance with a feature of the invention, the operators 38 are mounted Within the housing 32 by means of a snap fit. Further in accordance with the invention, each operator is provided with a cam portion generally designated as 44 serving not only to control the separation of terminals 36, but also serving to index the operator 38 in its open circuit and closed circuit positions.

Proceeding now to a more detailed description of the switch assembly 20, the housing 32 and base 34 cooperate to enclose the cavity 40. The housing 32, base 34 and operator 38 may be formed of any suitable material, such as a molded plastic. The housing 32 comprises a unitary, generally boxshaped body including a top wall 46, a pair of opposed side walls 48, and a pair of opposed end walls 50.

Base 34 includes a planar wall portion 52 flanked at each side by a flange or lip wall 54. The open bottom of housing 34 is closed by attaching the base 32 to the housing 32, and preferably this is accomplished with a snap. fit in order to avoid the necessity for fasteners, ad-

hesives or the like. The outer surface of each flange 54 is provided with a ridge or projection 56 received in a corresponding groove 58 in each side wall 48.

Chamber 40 is subdivided into individual switch compartments by a seies of intermediate wall structures 62 parallel with the end walls 50. The outermost wall structures 62 may be formed integrally with the end walls 50 in order to provide a compact arrangement. Wall structures 62 serve both to locate andto separate pairs of the terminals 36, and also to support the operators 38.

As indicated above, each of the terminals 36 is of identical construction. Each is formed, for example by a series of punch press operations, from a flexible resilient metal such as phosphor bronze and includes a genextending from the end of the base portion 64 to a generally flat or straight segment 70 angularly related to the base portion 64. An additional bend or fold 72 interconnects the flat 70 with an additional flat or straight segment 74 having a rounded end 76 abutting the base portion 64. Due to the flexibility and resiliency of the material from which the terminals 36 are made,

1 each spring contact portion 66 may be resiliently compressed inwardly toward the base portion 64 from the relaxed position illustrated in FIG. 7.

In order to retain the terminals 36 in position within the cavity 40, each terminal is provided with a pair of side flanges or extensions 78 received within recesses or grooves 80 formed at the junctions of the intermediate walls 62 and the side walls 48. Moreover, each terminal 38 is provided with a stop 82 struck from the base portion 64 and engageable with one of a series of corresponding bosses 53 located on the upper edge of the flanges or lip walls 54, as best seen in FIGS. 3 and 6.

The terminals 36 are formed so that in their relaxed condition each spring contact portion 66 has a lateral dimension somewhat greater than half the distance across cavity between the side walls 48. Thus, when a pair of terminals 36 are mounted in opposed positions within the cavity 48, the two terminals abut against one another in order to complete an electrical circuit between their two male contact portions 30. After assembling the parts of the switch assembly 20, each pair of terminals36 is maintained in this position. More specifically, each terminal is prevented from moving upwardly by engagement of the bend segment 68 with the housing top wall 46, and is prevented from downward movement by engagement of the stop 82 with the boss 53 on lip wall 54. Moreover, the terminals are resiliently biased against the side walls 48 either by another terminal in the closed circuit condition of FIG. 3, or by the cam portion 44 of the operator 38 in the open position of FIG. 6.

In the illustrated embodiment of the invention, the male contacts 30 are adapted tobe interconnected with circuitry on a printed circuit board by any conventional soldering process. It should be understood that other contact configurations could be provided for other types of electrical connections to the switch assembly. Since the illustrated assembly 20 is intended for connection by soldering, the planar wall portion 52 of the base 34 is provided with openings 84 through which the male contacts 30 extend, and these openings provide substantial clearance around the contact portions to prevent wicking or capillary flow of solder into the cavity 40. The exterior wall of the base 34 is provided with projections 51 to maintain a space between the bottom of the assembly and a printed circuit board for the escape of gases, fluxes and the like produced during the soldering operation.

Operation of each of the individual switches 22, 24, 26 and 28 between the closed circuit condition and the open circuit condition is effected by means of one of the switch operators 38. Each switch operator includes a pair of trunnion elements 86 for mounting the operator for pivotal movement about an axis located between and parallel to the planes of the side walls 48. As can best be seen in FIGS. 3 and 6, the axis of rotation in the illustrated arrangement lies above the point of contact between adjacent spring contact portions 66 of terminals 36. An operating element or operating arm 88 extends radially outward from the axis defined by trunnion elements 86 through an opening 90 provided in the top wall 46 of the housing 32. Each arm 88 is provided with an indicator flag projection 92 for providing a visual indication of the operational condition of the switch.

One important advantage of the switch assembly 20 of the present invention is that is easily manufactured with a minimum of labor. One reason for the simplicity of the assembly operation is the provision in accordance with the invention of a snap fit mounting of the switch operators 38 in the housing 32. Each intermediate wall structure 62 is provided with a generally circular bearing wall 94 for receiving trunnion elements 86 of the operators 38. The bearing wall 94 is defined at its lowermost region by means of a pair of relatively thin and therefore somewhat flexible wall members 96. The circular bearing wall 94 is in the form of a segment of a circle rather than a complete circle due to an entry gap 98 defined between the ends of the thin wall members 96. Gap 98 is somewhat narrower than the diameter of the trunnion elements 86.

During assembly of each switch structure, the operator 38 is inserted into the housing 32 through the open bottom wall prior to mounting of the base 34. The actuating arm 88 is guided through the corresponding opening 90 and the opposed trunnion elements 86 are directed toward the gap 98. The operator 38 is pushed upwardly relative to the housing 32 and the trunnion elements 86 are received with a snap action into the bearing walls 94 due to an interference fit between the trunnion elements 86 and the flexible wall members 96. This arrangement not only avoids the necessity for mounting structure in addition to portions integral with the operators 38 and housing 32, but also readily lends I portion 44 generally surrounds the axis of the trunnion elements 86 in the region opposite the projecting actuating arm 88. The cam portion 44 defines a cam surface including first, second, third and fourth generally flat surface portions 100, 102, 104 and 106 respectively.

In the closed circuit condition of the switch shown in FIG. 3, the flats 100 and 104 are generally parallel to the flat portions 70 of the spring contact portions 66 of the two corresponding terminals 36. The flats 100 and 104 are spaced from the rotational axis of the operator 38 by a distance such that the cam portion 44 does not compressthe terminals 36 and the spring contacts 66 are maintained in their abutting, closed position.

When the actuating arm 88 is moved from its position in'FIG. 3 to the position illustrated in FIG. 6, the alternate flats 102 and 106 are brought into engagement with the corresponding terminals 36 Since surfaces 102 and 106 are spaced farther from the rotational axis of the switch operator 38 than the surfaces 100 and 104, the spring contact portions are forced apart in this position of the operator 38.

The cam portion 44 includes relatively rounded corners or zones of intersection 108 and 110 located respectively between surfaces 100 and 102 and surfaces 104 and 106. These rounded corners facilitate movement of the operator 38 between the open circuit and closed circuit conditions. Conversely, a relatively sharp zone of intersection or corner 112 is provided between the flats 102 and 104. The corner 112 resists overtravel of the operator 38 beyond the open circuit and closed circuit positons. Moreover, it should be noted that=the opening 90 is shaped to prevent substantial overtravel of the acutating arm 88 beyond its alternate positions. The operator 38 is resiliently maintained in each of its two positions by the contours of the cam portion 44 and of the terminals 36. More specifically, in the closed circuit condition of FIG. 3, the flats 100 and 104 interface with the flat segments 70 of the terminals 36 to resiliently maintain the operator 38 in the illustrated position. Similarly, as illustrated in FIG. 6, the flats 102 and 106 cooperate with flat segments 70 resiliently to maintain the operator in the open, circuit position. In either position, in order to rotate the operator to the'other position, it is necessary to move the rounded corners 108 and 110 across the flat segments 70, and the resiliency of the spring contact portions 66 provides an indexing or retaining force as well as a desirable feel of switch operation. 1

One important advantage of the switch assembly 20 is that it provides reliable, long lasting,.low resistance contact operation. Adjacent spring'ter'minal contact portions 66 are-resiliently biased together in abutting relation in the closed circuit condition to provide reliable electrical contact. As the operator 38 is pivoted to the alternate position, the contact portions 66 are sepato the closed condition, a slightwiping action is assured because the contacts 66 are separated in a nonsymmetrical fashion. However, the disadvantages of sliding contact operation are avoided. If desired, the contact surfaces of the terminals 36 may be plated with gold further to reduce contact resistance. In this regard it should be noted that the operator 38 does not wear off the plating material.

Having reference now to FIGS. 8 and 9, there is illustrated a switch assembly generally designated as 120 and comprising an alternative embodiment of the invention. In many respects the assembly 120 is identical to the assembly 20 and identical partsare'provided with identical reference numerals. In accordance with the invention, the switch assembly 120 is provided with a cover member generally designated as 122 for protecting the components of the switch assembly 120 and for preventing inadvertent operation of any of the individual switches. Also in accordance with the invention, the cover 122 permits visual inspection of the operational condition of the switching assembly 120.

More specifically, the assembly 120 includes a housing 124 which may be identical to the housing 32 described above except that it is provided with a pair of recesses 131 located in the outer surfaces of the end .walls50. Cover member 122 comprises a generally box-shaped unitary body 'complementaryin form to the housing 124 and adapted to fit thereover'in telescoping arrangement. End walls 126 of the cover 122 include angular ridges or projections 130 receiving theridges 131 in order to permit mounting of the cover 122 on the housing 124 with a snap fit. it will be apparent that the force required to remove cover 122 from housing 124 should be substantially less than the force which would be necessaryto remove the housing 124 from the base 34.

In accordance with one feature of the invention, a top wall 132 of the cover 122 is provided with an inwardly directed projection 134 overlying the row of openings through which the actuating arms 88 extend. The projection 134, when the cover is in place, obstructs the region through which the arms 88 move between their alternate positions, so that inadvertent operation of the arms is impossible.

In order to permit visual inspection of the switch assembly so that the position of each actuating arm 88 can readily be determined, preferably'the cover member 122 is formed of a transparent material. For example, the cover member may be formed of a molded plastic such as a clear polycarbonate or the like.

While the invention has been described with reference to details of the illustrated embodiments, it should be understood that such details do not limit the scope of the invention as defined in the following claims.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. A switch assembly comprising:

a housing including a top wall and opposed side walls defining a cavity;

a pair of similar terminals mounted in said cavity, each including a spring contact portion having a base and a loop extending from said base;

said basesbeing'positioned against said opposed side walls and said loops extending toward one another within said cavity, portions of said loops normally abutting one another; 3

a switch operator pivotally mounted within said cavity for rotational movement between first and second positions about an axis between said side walls and generally parallel to said side and top walls; and v cam means on said operator engageable with at least one said spring contact portion for separating said contact portions upon pivoting of said operator from'said first to said second position.

2. The assembly of claim 1, a plurality of said pairs of terminals and of said operators.

3. The assembly of claim 2, said housing including an open bottom, and a base member attached to said housing to close said bottom, said housing and said base member having latching means so that said hous ing and said base member may be attached with a snap fit.

4. The assembly of claim 3, each terminal including an additional contact portion extending from said housing out of said cavity through said base member.

5. The assembly of claim 4, said additional contact portions comprising solder tails disposed in two parallel rows.

6. The assembly of claim 1, further comprising indexing surface means on said cam means and said loop portions for resiliently retaining said operator in said first and second positions.

7. The assembly of claim 1, a pair of trunnions on said operator, and wall means integral with said housing forming an opposed set of bearings, said wall means and bearings being constructed and arranged for a snap fit of said trunnions into said bearings.

8. A switch assembly comprising:

a housing including a top wall and opposed side walls defining a cavity;

a plurality of pairs of similar terminals mounted in said cavity, each terminal including a spring contact portion having a base and a loop extending from said base;

said bases being positioned against said opposed side walls and said loops of each pair of terminals extending toward one another within said cavity, portions of said loops normally engaging one another;

a plurality of switch operators pivotally mounted within said cavity for rotational movement between first and second positions about an axis between said side walls and generally parallel to said side and top walls;

cam means on each said operator engageable with at least one said spring contact portion of each pair of terminals for separating said contact portions upon pivoting of said operator from said first to said second position,

each said operator including an actuating arm extending radially from said axis through said top wall;

a cover member releasably engeable with said housing and overlying said top wall;

and projection means on said cover in the path of movement of said actuating arms for preventing pivoting of said operators between positions when said cover is in place.

9. The assembly of claim 8, said cover member being I means for supporting said operator member in said bearings for pivotal movement, terminal means supported in said housing and including switch contact means, and cam means on said operator member engageable with said contact means for operating said contact means between open and closed conditions in response to pivotal movement of said operator memher, said wall means each including a bearing wall in the form of a segment of a circle having an entry gap therein, the portions of said bearing wall adjacent said entry gap being defined by a pair of flexible wall portions, and said trunnion means comprising a pair of trunnion shafts extending from opposed sides of said operator member and having a diameter larger than said entry gap, thereby allowing a snap fit between the trunnions and the bearing means.

11. The assembly of claim 10, said housing including a top wall, opposed side walls and opposed end walls, said wall means comprising first and second wall structures integral with said end walls and at least one intermediate third wall structure parallel to and spaced from said first and second wall structures, and at least two said operators disposed between and supported by said first, second and third wall structures.

12. The assembly of claim 11, said housing having an open bottom, said entry gaps being directed toward said bottom.

13. The assembly of claim 12 further comprising a base member engageable with said side walls and end walls to close said open bottom.

14. A switch assembly comprising a housing having an interfacing pair of walls, a cavity between said walls, a pair of similar terminals mounted in said cavity, each terminal including a generally flat base portion and a loop portion overlying the base portion, said base portions being positioned against said walls and said loop portions extending toward one another within said cavity, portions of said loops normally engaging one another, a switch operator mounted for rotation about an axis between and generally parallel to the planes of said walls, cam means on said operator for separating said loop portions upon rotation of said operator from a first to a second position, and indexing surface means on said cam means and said loop portions for resiliently retaining said operator in said first and second positions, said loop portions each including a terminal surface directed toward said cam means, said cam means including first, second, third and fourth cam surfaces,

said first and third cam surfaces engaging said terminal surfaces in the first operator position and said second and fourth cam surfaces engaging said terminal surfaces in the second operator position, each of said terminal surfaces and said first, second, third and fourth cam surfaces being generally flat.

15. The assembly of claim 14, further comprising a pair of rounded corners, one joining said first and second cam surfaces and the other joining said third and fourth cam surfaces, and a sharp corner joining said second and third cam surfaces.

16. A switch assembly comprising in combination a housing having an exterior surface, opening means in said surface extending in a first direction, a plurality of switch operating elements extending through said opening means and out of said housing, said housing including means engageable with said elements and tween first positions and second positions, switching means in said housing operable between closed circuit and open circuit conditions in response to movement of said elements between said first and second positions, and a cover removably engageable with said housing and overlying said surface, said cover including obstruction means located between said first and second positions for preventing movement of said elements between positions when said cover is in place.

17. The assembly of claim 16, switch position indicator means on said operating elements, said cover being formed of transparent material.

.18. The assembly of claim 16, said operating elements comprising arms pivotable around a common axis within said housing parallel with said first direction.

19. A switch assembly consisting essentially of a first part, a second part, a plurality of substantially identical third parts, and a plurality of substantially identical fourth parts;

said first part comprising a generally box-shaped housing having an open bottom wall and including integral opposed bearings formed therein;

said second part comprising a removable bottom wall for said housing;

said third parts each comprising a switch operator having trunnions received in said bearings, having an eccentric cam carried by said trunnions, and having an operating lever extending from said housing for rotating said operator between first and second positions; and

said fourth parts each comprising a conductive terminal having a spring contact portion within said housing and an additional contact portion extending from the housing, said spring contact portions being arranged in pairs, each pair being mounted adjacent one said cam for movement between closed and open positions in response to rotation of said operator.

20. In combination, the switch assembly of claim 19 and a cover releasably engageable with said housing for covering the portion of said housing from which said operating levers extend. 

1. A switch assembly comprising: a housing including a top wall and opposed side walls defining a cavity; a pair of similar terminals mounted in said cavity, each including a spring contact portion having a base and a loop extending from said base; said bases being positioned against said opposed side walls and said loops extending toward one another within said cavity, portions of said loops normally abutting one another; a switch operator pivotally mounted within said cavity for rotational movement between first and second positions about an axis between said side walls and generally parallel to said side and top walls; and cam means on said operator engageable with at least one said spring contact portion for separating said contact portions upon pivoting of said operator from said first to said second position.
 2. The assembly of claim 1, a plurality of said pairs of terminals and of said operators.
 3. The assembly of claim 2, said housing including an open bottom, and a base member attached to said housing to close said bottom, said housing and said base member having latching means so that said housing and said base member may be attached with a snap fit.
 4. The assembly of claim 3, each terminal including an additional contact portion extending from said housing out of said cavity through said base member.
 5. The assembly of claim 4, said additional contact portions comprising solder tails disposed in two parallel rows.
 6. The assembly of claim 1, further comprising indexing surface means on said cam means and said loop portions for resiliently retaining said operator in said first and second positions.
 7. The assembly of claim 1, a pair of trunnions on said operator, and wall means integral with said housing forming an opposed set of bearings, said wall means and bearings being constructed and arranged for a snap fit of said trunnions into said bearings.
 8. A switch assembly comprising: a housing including a top wall and opposed side walls defining a cavity; a plurality of pairs of similar terminals mounted in said cavity, each terminal including a spring contact portion having a base and a loop extending from said base; said bases being positioned against said opposed side walls and said loops of each pAir of terminals extending toward one another within said cavity, portions of said loops normally engaging one another; a plurality of switch operators pivotally mounted within said cavity for rotational movement between first and second positions about an axis between said side walls and generally parallel to said side and top walls; cam means on each said operator engageable with at least one said spring contact portion of each pair of terminals for separating said contact portions upon pivoting of said operator from said first to said second position, each said operator including an actuating arm extending radially from said axis through said top wall; a cover member releasably engeable with said housing and overlying said top wall; and projection means on said cover in the path of movement of said actuating arms for preventing pivoting of said operators between positions when said cover is in place.
 9. The assembly of claim 8, said cover member being transparent.
 10. A switch assembly comprising a housing, wall means integral with said housing forming an opposed set of bearings, an operator member having trunnion means for supporting said operator member in said bearings for pivotal movement, terminal means supported in said housing and including switch contact means, and cam means on said operator member engageable with said contact means for operating said contact means between open and closed conditions in response to pivotal movement of said operator member, said wall means each including a bearing wall in the form of a segment of a circle having an entry gap therein, the portions of said bearing wall adjacent said entry gap being defined by a pair of flexible wall portions, and said trunnion means comprising a pair of trunnion shafts extending from opposed sides of said operator member and having a diameter larger than said entry gap, thereby allowing a snap fit between the trunnions and the bearing means.
 11. The assembly of claim 10, said housing including a top wall, opposed side walls and opposed end walls, said wall mans comprising first and second wall structures integral with said end walls and at least one intermediate third wall structure parallel to and spaced from said first and second wall structures, and at least two said operators disposed between and supported by said first, second and third wall structures.
 12. The assembly of claim 11, said housing having an open bottom, said entry gaps being directed toward said bottom.
 13. The assembly of claim 12 further comprising a base member engageable with said side walls and end walls to close said open bottom.
 14. A switch assembly comprising a housing having an interfacing pair of walls, a cavity between said walls, a pair of similar terminals mounted in said cavity, each terminal including a generally flat base portion and a loop portion overlying the base portion, said base portions being positioned against said walls and said loop portions extending toward one another within said cavity, portions of said loops normally engaging one another, a switch operator mounted for rotation about an axis between and generally parallel to the planes of said walls, cam means on said operator for separating said loop portions upon rotation of said operator from a first to a second position, and indexing surface means on said cam means and said loop portions for resiliently retaining said operator in said first and second positions, said loop portions each including a terminal surface directed toward said cam means, said cam means including first, second, third and fourth cam surfaces, said first and third cam surfaces engaging said terminal surfaces in the first operator position and said second and fourth cam surfaces engaging said terminal surfaces in the second operator position, each of said terminal surfaces and said first, second, third and fourth cam surfaces being generally flat.
 15. The assembly of claim 14, further comprising a pair of rounded cornErs, one joining said first and second cam surfaces and the other joining said third and fourth cam surfaces, and a sharp corner joining said second and third cam surfaces.
 16. A switch assembly comprising in combination a housing having an exterior surface, opening means in said surface extending in a first direction, a plurality of switch operating elements extending through said opening means and out of said housing, said housing including means engageable with said elements and mounting said elements for movement in a second direction generally transverse to said first direction between first positions and second positions, switching means in said housing operable between closed circuit and open circuit conditions in response to movement of said elements between said first and second positions, and a cover removably engageable with said housing and overlying said surface, said cover including obstruction means located between said first and second positions for preventing movement of said elements between positions when said cover is in place.
 17. The assembly of claim 16, switch position indicator means on said operating elements, said cover being formed of transparent material.
 18. The assembly of claim 16, said operating elements comprising arms pivotable around a common axis within said housing parallel with said first direction.
 19. A switch assembly consisting essentially of a first part, a second part, a plurality of substantially identical third parts, and a plurality of substantially identical fourth parts; said first part comprising a generally box-shaped housing having an open bottom wall and including integral opposed bearings formed therein; said second part comprising a removable bottom wall for said housing; said third parts each comprising a switch operator having trunnions received in said bearings, having an eccentric cam carried by said trunnions, and having an operating lever extending from said housing for rotating said operator between first and second positions; and said fourth parts each comprising a conductive terminal having a spring contact portion within said housing and an additional contact portion extending from the housing, said spring contact portions being arranged in pairs, each pair being mounted adjacent one said cam for movement between closed and open positions in response to rotation of said operator.
 20. In combination, the switch assembly of claim 19 and a cover releasably engageable with said housing for covering the portion of said housing from which said operating levers extend. 